Anomalies Of Phase Diagrams And Physical Properties Of Antiferrodistortive Perovskide Oxides

TL;DR

This review explores how rotomagnetic, rotoelectric, and magnetoelectric couplings influence phase diagrams and properties of antiferrodistortive perovskite oxides, revealing novel multiferroic phases and effects in nanosystems and thin films.

Contribution

It provides a comprehensive analysis of coupling effects on phase behavior and predicts new multiferroic phases in AFD perovskites using LGD theory, including size and interface phenomena.

Findings

Induction of FM and FE phases via ME coupling in EuTiO3.

Prediction of triple AFD-FE-FM(AFM) phases in nanosystems.

Size-induced increase of AFM transition temperature in BiFeO3 ceramics.

Abstract

The influence of rotomagnetic (RM), rotoelectric (RE) and magnetoelectric (ME) coupling on phase diagram and properties of antiferrodistortive (AFD) perovskite oxides was reviewed. The main examples we consider in the review are typical AFD perovkites, such as incipient ferroelectrics EuTiO3, SrTiO3, EuxSr1-xTiO3, multiferroic BiFeO3 and Bi1-xRxFeO3 (x = La, Nd). The strong influence of RM, RE and ME couplings on the physical properties and phase diagrams including antiferromagnetic (AFM), ferroelectric (FE) and structural AFD phases has been revealed in the framework of Landau-Ginzburg-Devonshire (LGD) theory, as well as the prediction of novel (double and triple) multiferroic phases has been demonstrated. In the review we are especially focused on (a) the possibility to induce FM (FE) phase in EuTiO3 (as well as in other paraelectric AFM oxides) by the application of an electric (magnetic) field due to the ME coupling; (b) the analysis of the size effects and novel phases in EuxSr1-xTiO3 nanosystems, where the LGD predicts the presence of the triple AFD-FE-FM(AFM) phase at low temperatures; (c) the appearance of improper spontaneous polarization and pyroelectricity in the vicinity of antiphase domain boundaries, structural twin walls, surfaces and interphases in the AFD phase of non-ferroelectric SrTiO3 induced by the flexoelectricity and rotostriction; (d) the occurrence of low symmetry monoclinic phase with in-plane FE polarization in thin strained EuxSr1-xTiO3 films and its stabilization over wide temperature range by AFD oxygen octahedron tilts due to flexoelectric and rotostriction coupling; (e) discussion of a surprisingly strong size-induced increase of AFM transition temperature caused by the joint action of RM coupling with elastic stress accumulated in the intergrain spaces of BiFeO3 dense ceramics.